The Journal of Headache and Pain 2013, 14:2
doi:10.1186/1129-2377-14-2

Published: 24 January 2013

Abstract

Background

A single intake of monosodium glutamate (MSG) may cause headache and increased muscle
sensitivity. We conducted a double-blinded, placebo-controlled, crossover study to
examine the effect of repeated MSG intake on spontaneous pain, mechanical sensitivity
of masticatory muscles, side effects, and blood pressure.

Methods

Fourteen healthy subjects participated in 5 daily sessions for one week of MSG intake
(150 mg/kg) or placebo (24 mg/kg NaCl) (randomized, double-blinded). Spontaneous pain,
pressure pain thresholds and tolerance levels for the masseter and temporalis muscles,
side effects, and blood pressure were evaluated before and 15, 30, and 50 min after
MSG intake. Whole saliva samples were taken before and 30 min after MSG intake to
assess glutamate concentrations.

Conclusion

In conclusion, MSG induced mechanical sensitization in masseter muscle and adverse
effects such as headache and short-lasting blood pressure elevation for which tolerance
did not develop over 5 days of MSG intake.